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KMID : 0380220060390040452
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Journal of Biochemistry and Molecular Biology
2006 Volume.39 No. 4 p.452 ~ p.456
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Oxidative Damage of DNA Induced by the Cytochrome c and Hydrogen Peroxide System
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Kim Nam-Hoon
Kang Jung-Hoon
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Abstract
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To elaborate the peroxidase activity of cytochrome c in the generation of free radicals from H2O2, the mechanism of DNA cleavage mediated by the cytochrome c/H2O2 system was investigated. When plasmid DNA was incubated with cytochrome c and H2O2, the cleavage of DNA was proportional to the cytochrome c and H2O2 concentrations.Radical scavengers, such as azide, mannitol, and ethanol, significantly inhibited the cytochrome c/H2O2 systemmediated DNA cleavage. These results indicated that free radicals might participate in the DNA cleavage by the cytochrome c and H2O2 system. Incubation of cytochrome c with H2O2 resulted in a time-dependent release of iron ions from the cytochrome c molecule. During the incubation of deoxyribose with cytochrome c and H2O2, the damage to deoxyribose increased in a time-dependent manner, suggesting that the released iron ions may participate in a Fenton-like reaction to produce ·OH radicals that may cause the DNA cleavage. Evidence that the iron-specific chelator, desferoxamine (DFX), prevented the DNA cleavage induced by the cytochrome c/H2O2 system supports this mechanism. Thus we suggest that DNA cleavage is mediated via the generation of ·OH by a combination of the peroxidase reaction of cytochrome c and the Fenton-like reaction of free iron ions released from oxidatively damaged cytochrome c in the cytochrome c/H2O2 system.
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KEYWORD
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Cytochrome c, DNA, Fenton Reaction, Peroxidase
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